Science advances rapidly, and with it, our visions of the future.  People have been dreaming about traveling to outer space for thousands of years, and their dreams have necessarily been based on extrapolations of the time.  For instance, when Daedalus and Icarus made their flights, they used bird-like wings.  What else was there?  When Jules Verne wrote about a trip to the moon, a giant cannon was the propulsion. 

Then the rocket came along, and that became the vehicle of choice for space jaunts.  Yet the portrayal of rockets in science fiction even just a few years ago differs dramatically from how they ended up actually being used for space travel.  One crucial development changed the whole game in the span of just five years.

Two books in my library illustrate what I'm talking about.  In 1953, Jeffery Lloyd Castle wrote Satellite E One, and Murray Leinster wrote Space Tug, both near-future tales of space stations.  In the beginnings of both books, our heroes are blasted into orbit with the use of rockets—lots of rockets.  Castle's booster is 150 feet tall and has 50 rocket engines.  Leinster's is even more creative.  Dozens of independent jet engines propel the rocket assembly to about 12 miles up and then detach, whereupon solid rockets fire and subsequently detach.  Finally, the rocket's own engines (presumably liquid fuel) ignite to finish the journey.

Both of these stories are products of their era.  Until 1953, rockets were pretty small affairs.  In the 30s, they were strictly hobbyists' stuff.  Even in the 40s, the vaunted German V-2 was what would now be classified a Short Ranged Ballistic Missile (SRBM).  Missile development languished in the early post-war compared to the prodigious effort expended on the development of jet engines.  To science fiction writers, it seemed any space rocket would have to be purpose-built, and it would take a tremendous number of these small engines to get a craft to orbit.  That's why most predictions saw humanity reaching the moon around the end of the century.  Clarke was particularly visionary in Childhood's End when he wrote about a manned lunar mission as early as 1975 using atomic rockets.

What few authors predicted was the InterContinental Ballistic Missile (ICBM) race.  In 1954, the Air Force and Army began working in earnest to develop titanic missiles to send nuclear warheads across the world.  Since all must crawl before walking, their first product was the Intermediate Ranged Ballistic Missle (IRBM), which will be based in Europe.  The Army finished their first proto-IRBM, the Redstone, in 1956.  All of a sudden, the United States had an off-the-shelf method to send payloads into orbit.  With the completion of the Thor and Jupiter IRBMs in 1957, as well as the Navy's Vanguard (not a military vehicle but based on the earlier Viking, in turn based on the V-2), America suddenly had a stable of boosters.

That year, the Soviet Union launched Sputnik.  They didn't use a purpose-built space booster; they borrowed an ICBM from their arsenal and stuck a satellite on top.  We know it was an ICBM for two reasons: the Soviets had, just a few months before, announced that they'd built and tested an ICBM.  And Sputnik III, which used the same launcher as Sputniks I and II (presumably) weighed a ton-and-a-half, so an ICBM class booster was needed to loft it.

We don't know how many individual rockets make up the Soviet booster, but the Redstone, Thor and Jupiter use just one.  Of course, it is more efficient to send multi-staged rockets into orbit, so the Juno-I that launched the first Explorer actually has 14 engines (the one on the Redstone and 13 solid-fueled Sergeants on top).  The Juno-II also has 14 (Jupiter plus 13 Sergeants).  The Junos are stopgaps, however.  The Thor-Able that launched Pioneers 0-2 only has three engines.  The first crop of American ICBMs, the Atlas and the Titan, have just 2-3 engines.  Even Von Braun's proposed lunar mission monsters will only have around 12, tops.  So much for cluster rockets with dozens of engines.

It is no coincidence that the Space Race started when it did.  It is a direct side-effect of the ICBM race.  Science fiction authors are going to have to revise their timetables as well as their portrayals of rockets.  It just goes to show that science progresses awfully fast when we want it to, sometimes faster than our ability to predict its progress.

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